Ceramic-plated metallic or composite materials consist of a metallic or composite substrate coated with ceramic. These materials are lightweight and, by virtue of the ceramic plating, exhibit markedly enhanced thermal strengths over the strength of the metallic or composite substrate alone. These properties have made them attractive materials for component fabrication in many industries such as aerospace, automotive, and military equipment industries, where lightweight thermally resistant structures are desired. For example, ceramic-coated metallic materials continue to be explored for use in gas turbine engine applications to reduce the overall weight of the engine and improve engine efficiency and fuel savings. However, the strength and performance characteristics of ceramic-plated materials may be dependent upon the integrity of the interfacial bond between the ceramic plating and the underlying metallic or composite substrate. As such, the ceramic coating may become disengaged from the substrate surfaces.
The interfacial bond strength between the ceramic plating and the underlying substrate also may be compromised upon exposure to high temperatures, such as those experienced during some high-temperature engine operations. If ceramic-coated components are exposed to temperatures over a critical temperature or critical temperature range during operation, the interfacial bond between the ceramic coating and the substrate may be at least partially degraded, which may lead to structural break-down of the component and possible in-service failure. To provide performance characteristics necessary for the safe use of ceramic-coated materials in gas turbine engines and other applications, strategies are needed to improve the interfacial bond strength and the high temperature stability of the ceramic-coated materials.
Transient liquid phase (TLP) and partial transient liquid phase (PTLP) bonding processes have been found to be useful alternatives to welding and brazing as ways to bond metals and ceramics. PTLP bonding is often performed with elemental interlayers designed to eventually form a solid solution after isothermal solidification and subsequent homogenization steps. However, the resulting strength of the solid-solution bond may not be sufficient for certain applications, especially in the aerospace industry. The present disclosure is directed to solving this problem by providing a method for achieving a stronger bond in a PTLP bonding process.